In general, the term “infusion” is understood as any administration of a liquid or solid substance and/or an infusing medium, such as pharmaceutical substances, cells, genes, enzymes, proteins, liposomes, antibodies, hormones, viral vectors, viruses or the like. The substance may be introduced directly into a body and/or into body tissues, for example, in order to reach a pre-defined target area and/or to bypass the effect of the blood-brain barrier. The substance can be delivered within a relatively short period of time, for example through an injection, or over a longer period of time, for example at a continuous and possibly variable rate of delivery of the substance.
Pharmaceutical substances previously have been administered by injecting a substance through the skin, directly into the vascular system, muscle tissue or subcutaneous tissue, or by positioning a catheter such that a substance could be introduced directly into the targeted body tissues. Administration depends on the experience of the person who positions the syringe or catheter so as to position or deliver the administered substance as precisely as possible in the desired area of tissue. Furthermore, the behavior of said substance in the specific area of tissue is known and taken into consideration to ensure that the resulting distribution of the substance matches the desired target area.
Due to intrinsic and unavoidable inaccuracies related to the planning and placement procedure (e.g., from image resolution registration inaccuracy, etc.), and to different levels of experience of the executing physician and/or the lack of knowledge of the patient-specific tissue configuration, as well as due to patient-specific variations in the arrangement of the tissue, for example in the case of a diseased tissue, it has been necessary to leave sufficient space between critical areas (in terms of a specific level of risk, automatically and/or manually defined) in order to ensure that the catheter does not interfere with the critical area. These areas include, for example, eloquent brain areas, vascular structures or anatomical areas such as ventricles or the optic nerve.
Another consideration is the actual trajectory of the catheter relative to the critical areas. Thus, although there might be a trajectory that avoids all non-desired areas and structures, this trajectory might not be chosen if it is in close proximity to critical areas. Therefore, to avoid the risk of injuring a critical area, the catheter is not placed as close as possible to an area to be treated.
On the other hand, when performing an infusion, it is preferable that the substance distribution resulting from the infusion optimally matches the desired target area. In the case of suboptimal catheter placement, this may necessitate that a larger amount of a toxic treatment substance is infused than would have been necessary if the catheter was placed in close proximity or directly into the area to be treated.
According to the prior art, trajectories for biopsies or intra-cranial catheters are planned prior to neurosurgery. The planning is based on target selection and on a selection of the entry point of the trajectory. To perform a minimally invasive surgical procedure, the physician plans the trajectory in consideration of critical brain areas. These areas might consist of critical and anatomical structures, such as ventricles, or physiological, vascular or functional structures.
Various methods and devices have already been proposed for enabling a substance to be introduced into a particular area of tissue, or for developing more efficient treatments that can be used to treat, for example, tumors, Parkinson's disease or other diseases.
It is known from U.S. RE 37,410 E to inject a substance to be administered into a biodegradable material and to arrange the latter within or closely adjacent to a tumor to be treated, in order for example to bypass the effect of the blood-brain barrier in the case of a brain tumor. Once the bio-degradable material has degraded, the substance contained therein is released. This delivery method based on diffusive processes, however, is relatively imprecise with respect to individual, patient-specific dosage.
U.S. Pat. No. 6,026,316 describes a method for delivering medicines using data obtained from magnetic resonance imaging (MRI) to determine the position of the delivery device and to monitor the spatial distribution of the delivered medicine.
US-2003-01-147051-A1 discloses a method for planning an infusion, wherein patient data is captured and the infusion to be carried out is planned using this patient data.